Exemplary embodiments relate to applying a next follow-on pin as a handling or processing pin to the stone to be cut, which is previously held by a preceding pin which serves for example as a measuring pin in preceding measurements on the stone to adapt the geometry of the rough stone to be cut, in particular a rough jewel, in the best possible fashion to a shape to be obtained for a cut jewel, or vice-versa.
The jewel, in its desired geometrically predetermined shape, should be utilised in the best possible fashion, with a reduction in the loss of rough volume (in particular it should be of a volume-optimised configuration).
The procedure which has been tried and tested and handed down for centuries for cutting rough uncut jewels operates with a pencil-like holding pin and a normal wooden block which serves as an apertured board for insertion of the wooden pin, to the tip of which the rough uncut stone is fixed with a drop of resin, wherein insertion of the pin into the apertured board defines an angle of inclination which is required for the cutting operation and which is to be maintained as uniformly as possible in the cutting operation and later upon polishing. DE-U 85 04 419 (Landgraf) depicts this operation, for example on page 1, middle paragraph. It is only then that the cut and the fire of the resulting cut jewel can be achieved or improved.
After cutting of the first half of the stone the wooden pin is released by the influence of temperature, in which case the resin softens and a pin-change procedure takes place in which the stone is held with another wooden pin which is to be freshly secured at a different location using the same procedure, also shown in Landgraf, page 18, FIG. 8 and page 19, last paragraph with the ideas of ‘changing cementing’ according to page 9, middle paragraph. For that purpose the stone is turned and on the wooden pin fixed thereto again fitted into the hole in the apertured board to be able to cut and polish the opposite side of the stone.
That side also requires the highest possible degree of consistency of maintaining the angle for the facets to be cut, the apertured board making it possible to adjust the cut angles in a raster grid of half a degree.
In the operation of changing pins in the foregoing sense, there is a change in the processing zenith, from the ‘northern hemisphere’ to the ‘southern hemisphere’ of the rough jewel to be cut. In that pin-changing operation the experienced operator is reliant on his own judgment, fingertip feel and his optical assessment to position the follow-on pin in the ‘pin-changing step’ at a location acceptable to him for the stone thermally released from the first pin, just as he is equally reliant in the ‘pin-fitting step’, that is to say applying the first wooden pin, on his own perception and experience. In that respect the relationship of the two pins to be applied does not involve a defined reproducible accuracy, or only that accuracy which the experienced cutter can bring to the first pin application step and the second pin application step.